This invention relates to a process for the consumable-electrode type arc cutting and to an apparatus to be used therefor.
The consumable-electrode type arc cutting process of the conventional principle uses the power unit of a DC arc welder as its power source, with one output terminal of the power unit connected to the wire electrode via the contact tip of the cutting torch and the other terminal connected to the work subjected to cutting, establishes a path of electric current through the wire electrode and the work to give rise to an arc therebetween to fuse and sever the work and simultaneuosly causes a shielding gas projected from the annular orifice surrounding the wire electrode to be blown against the work so as to shield the point of arc formation on the work against the ambient air and permits this operation of fusing and severing of the work to be carried out continuously by having the wire electrode paid out by means of the feed roller as the wire electrode is consumed by the arc. According to this process, however, the molten metal of the work hangs down from the bottom surface along the severed edges of the work to form what is called "dross." As the arc cutting of the work proceeds, the dross occurring immediately behind the port of arc formation on the work sometimes develops to the extent of joining the freshly severed edges of work and, on hardening, filling up the formed cut. In the case of a work having a relatively large thickness, this process has been found to experience difficulty in effecting the desired severance. Even in the case of a work having a small thickness, this process may cause the dross to adhere to the severed edges of the work and consequently prevent the cut portion of the work from being neatly finished.
An object of this invention is to provide a process for consumable-electrode type arc cutting which prevents the dross from being deposited on the severed edges of the work and permits the cut portion of the work to be finished neatly.
Another object of this invention is to provide a process for consumable-electrode type arc cutting which permits the severance of workpieces having thicknesses over a relatively wide range to be effected easily without allowing the severed edges to be joined again.
Still another object of this invention is to provide a process for consumable-electrode type arc cutting which permits the severance of the work to be accomplished as easily under water as in the atmosphere.
Yet another object of this invention is to provide a process for consumable-electrode type arc cutting which uses a constant voltage type power source or rising voltage type power source and therefore permits the severance of the work to be effected with the utmost safety from electric shock.